1. Field of the Invention
The present invention relates to a real-time diagnostic for determining laser induced breakdown events. More particularly, the present invention relates to an apparatus and a method that utilizes spectroscopic evaluation as a feedback means in real-time for determining optically produced three dimensional objects within an interaction volume.
2. Description of Related Art
The use of femtosecond lasers for micro-machining, waveguide writing,. microfluidic applications, and three-dimensional storage is a rapidly maturing field. Laser-based techniques have several marked benefits over traditional methods including, but not limited to, rapid device prototyping, cost effective production, and its simplicity for the construction of three-dimensional devices. The use of femtosecond lasers for micromachining/microfabricating applications offers distinct benefits compared to using other types of laser based systems, such as, for example, nanosecond excimer lasers due to better control of the energy deposition process. A persistent problem in machining structures at the smallest possible scale barrier arises in adequate control of the laser-material interaction volume leading to collateral material damage.
Background information on an existing three-dimensional storage using optical methods and apparatus is described in U. S. Pat. No. 4,466,080, entitled “Three Dimensional Patterned Media,” issued Aug. 14, 1984 to Sainson et al., including the following, “Method and active media for controlled production of physical and refractive index inhomogenetics in a volume of a suspension medium by use of at least two intersecting beams of electromagnetic radiation matched to the excited state properties of molecules in the media. In addition, complex three-dimensional physical and chemical structures are produced by selective excitation of different types of molecules in the media and by employing transportive capabilities of liquid or gaseous support medium.” However, such techniques from the above cited patent do not address detecting and quantifying laser-induced physical damage using spectroscopic analysis as a confirming tool in accordance with the principles of the present invention.
Accordingly, a need exists for methods and apparatus that can real-time monitor localized predetermined breakdown of desired material. Such monitoring apparatus and techniques as disclosed herein, enable micromachining/microfabrication writing processes within transparent materials and/or predetermined materials transparent to a use wavelength (e.g., ceramics) while undergoing predetermined laser intensities to improve process control and improve yield. The present invention is directed to such a need.